In today's telecommunications environment, there are many value-added services available to subscribers. This includes information altering services such as speed dial and distinctive ring, and transport altering services such as call forwarding and call waiting. In current telecommunication systems, a caller has access only to the value-added services that are provided by the transport provider to which the caller subscribes. The transport provider is the service that handles the switching of the information communicated from the calling party to the receiving party. As a result, any service not provided by the transport provider is not available to the caller. Thus, the current telecommunication environment limits a subscriber's ability to freely select these services and prevents subscribers from freely mixing and matching features from different carriers on a call by call basis or on a subscription basis. Moreover, current systems do not enable end-users, who have access/egress facilities to multiple competing carriers, to specify a particular carrier from which they want to receive incoming communications services.
The main cause of this limiting aspect of present day systems is the rigid communications environment dictated by the communication system architecture. This rigid environment is illustrated in the architecture of modem Integrated Services Digital Networks (ISDNs). A simplified view of the current architecture for ISDN is shown in FIG. 1. As shown, a subscriber can signal into the network to request calls (i.e. services and connections) through the User-Network Interface (UNI). This is done using the Digital Subscriber Signaling System No. 1 (DSS1) protocol suite over a dedicated point-to-point signaling link called the D-channel. The D-channel, and the entire DSS1 protocol suite, is terminated on the access switch to which the subscriber is physically connected. The user information, such as voice, travels over a separate logical channel, called the B-channel. Both the B- and D-channels occupy the same physical transmission media. See FIG. 2 for a simplified view of the ISDN message flow.
Within a network, nodes signal to each other across the Network Node Interface (NNI) using the Signaling System No. 7 (SS7) protocol suite over a common channel signaling network. The common channel signaling network consists of packet switches, called Signaling Transfer Points (STPs), that interconnect intelligent nodes and switches in a highly reliable configuration. Signaling information is transported between processors through different switches, and likely different transmission media, than the user information. The signaling messages, however, are routed to and processed within the switches that will eventually support the connection carrying the user information. Consequently, in present day systems, the routing of the signaling messages is dependent on the route of the user connection.
It is this relationship which allows only the providers supplying the transport service of the user information on a particular call to offer the signaling dependent services on that call (i.e. automatic call back, distinctive ring/call screening, speed dial, and repeat dial). As described above, this limits the subscriber's choices of services and service providers. That is, the subscriber may only choose services that are available from its transport provider.
A solution to this problem, called direct signaling, was presented by T. LaPorta and M. Veeraghavan in an article entitled "Direct Signaling: A New Access Signaling Architecture," in Proc. IEEE ICC '95, Seattle; Wash., 1995. Basically, direct signaling provides the ability to route and process signaling information independent of the transport information for a particular call. As a result, through a direct signaling architecture, subscribers can send their signaling messages to request services and connections directly from any service provider, independent of their particular access transport provider. Likewise, subscribers may receive signaling messages, and hence services, from any service provider for incoming calls, independent of their access transport provider. Consequently, the direct signaling approach enables subscribers to choose from a variety of service providers for their signaling services, without having to subscribe to each provider individually for a particular call.
One implementation of the direct signaling approach was disclosed in U.S. Pat. No. 5,473,679 issued to La Porta et al. on Dec. 5, 1995 (hereinafter LaPorta '679), and incorporated herein by reference. LaPorta '679 recognized that the root cause of the aforementioned prior art limitations on value-added service selection is the dependency of end-user signaling systems on end-user switching points. Specifically, the end-user switching points originate, process and terminate signaling messages for end-user devices. Because of that dependency, the end points for user signaling are switching systems that are generally managed and owned by a single communications carrier, such as a Local Exchange Carrier (LEC), a cellular communications provider or a cable television operator. Thus, the communications carrier that controls the local loop associated with the terminal device of a subscriber also controls the nature and type of signaling messages for all communications services received and requested by that subscriber over that loop. Hence, La Porta '679 recognizes that a subscriber in present day systems is at the mercy of the loop-controlling communications carrier (transport provider) for the type of communications services and features available to that subscriber.
As a result, La Porta '679 disclosed a communication network architecture in which, a subscriber is allowed to select a signaling provider independently of a) the transport carriers which control the local loops (transport providers) for particular communication services, and b) the providers of those services. Basically, the architecture enables bi-directional signaling messages associated with communications services requested by, or destined for a subscriber's terminal device to be sent unprocessed to a signaling provider selected by the subscriber. The signaling provider then requests those services from the specific service providers selected by the subscriber.
To achieve this, La Porta '679 describes a new telecommunications architecture wherein the user establishes a signaling connection to a node of a signaling provider of his or her choice via a transport provider network. The signaling provider node processes call setup signaling messages to determine the type of connections and services desired by the user, and then retrieves a profile associated with the terminal device or user-identification information contained in a signaling message. Through a look-up table operation, the profile identifies the particular features and service providers selected by the user, on a call by call basis or on a subscription basis. Once the appropriate service providers have been identified, the signaling provider node initiates and transmits service request signals to each of the signaling nodes of those service providers networks to obtain the requested services and establish the appropriate connections for the user's call.
To implement the La Porta '679 direct signaling system in current systems, however, would require substantial hardware changes/additions to both the local transport provider network and all the switching nodes along the communication path. More specifically, a MUX/DEMUX switch would have to be installed at each transport provider (i.e. LEC), a signaling service provider node (SSP) would have to be added to each signaling service provider, and a signaling service node (SSN) would have to be added to each service provider along the communication path. Thus, it would be substantially costly to incorporate the La Porta '679 system into the architecture of present day systems.
Another implementation of the direct signaling approach was disclosed in pending application Ser. No. 08/164521, filed by La Porta et al. on Dec. 9, 1993 (hereinafter La Porta '521), and incorporated herein by reference. La Porta '521 discloses another network architecture for providing direct signaling. Basically, LaPorta '521 calls for the integration of a signaling transfer device (STD) in the system architecture. The STD is electrically coupled between the subscriber device and the carrier network to which the subscriber communicates. For outgoing calls, the STD detects signaling indicia generated by the subscriber device and forwards those signaling indicia to a signaling provider network via the access facilities of a selected communications network. Upon receiving the signaling information, the signaling provider network processes that information, and returns to the STD other information that is used for the delivery of the communications to the user. Thus as with the La Porta '679 architecture, to implement the La Porta '521 system in present day systems would require substantial hardware costs.
Moreover, neither the LaPorta '679 nor the LaPorta '521 system disclose specific details of how the direct signaling procedures are actually implemented. La Porta '679 describes the use of a MUX/DEMUX switch and a SSP node, but does not give the specifics of the operation of these hardware devices. Similarly, La Porta '521 describes hardware implementations, but no details of their operation (e.g. how the system actually provides the value-added services to the subscriber on a particular call).